Bis(trimethylolpropane diallyl ether) dilinoleate and its phosphonates and lubricant compositions



United States Patent 3,423,319 BIS(TRIMETHYLOLPROPANE DIALLYL ETHER) DILINOLEATE AND ITS PHOSPHONATES AND LUBRICANT COMPOSITIONS Winfred E. Parker, Philadelphia, and Ronald E. Koos, Lansdale, Pa., assignors to the United States of America as represented by the Secretary of Agriculture No Drawing. Filed Aug. 18, 1966, Ser. No. 573,428 US. Cl. 25249.8 17 Claims Int. Cl. C10m /06 ABSTRACT OF THE DISCLOSURE The invention provides thermally stable lubricant compositions having good antiwear properties prepared from mixtures of esters of dimer acids and their phosphonates.

A non-exclusive, irrevocable, royalty-free license in the invention herein described, throughout the world for all purposes of the United States Government, with the power to grant sublicenses for such purposes, is hereby granted to the Government of the United States of America.

This invention relates to esters of dimer acids and their phosphonates and more particularly to the diallyl ether esters of dimer acids and their phosph-onates.

An object of the invention is to prepare thermally stable fluids for use as extreme pressure and base oil lubricants, lubricant additives, hydraulic fluids and the liquid phase of gas-liquid chromatographic columns.

Another object of the invention is to formulate thermally stable compositions for use as extreme pressure, antiwear lubricants.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims.

Effective lubricants for any type of machinery should be capable of performing their function over long periods of time without appreciable changes in their physical and chemical characteristics. Mineral hydrocarbon lubricating oils are not suitable for many lubrication problems of modern industry. Consequently, synthetic lubricants, such as bis(Z-ethylhexyl) sebacate and dibenzyl sebacate, employed as controls for evaluating the compounds of the present invention, have been prepared and used as specialty products. There is, however, continued need for better and. more effective lubricants and lubricant additives capable of sustained performance under more demanding operating conditions.

The compounds of the present invention are represented by the tformula:

wherein R is the diacyl radical derived from dimerized linoleicacid or the hydrogenated product thereof, R represents CH CH or and R" is any straight or branched chain aliphatic alkyl radical containing 1 to 8 carbon atoms. These compounds and the lubricant compositions formulated with these compounds as additives are thermally stable and represent a marked improvement in performance characteristics as evaluated by wear test and extreme pressure tests.

Antiwear properties were determined using the Shell Four Ball Wear Tester as described by Peale et al.,

3,423,319 Patented Jan. 21, 1969 ice American Society of Lubrication Engineers Transactions 3, 48 (1960). Approximately 10 ml. of the test oil were placed in the test cup so that the three bottom stationary balls were covered to about a 2 mm. depth. After positioning the cup on its stand in contact with the fourth ball, the oil was heated to 120 C., a 50 kg. load was placed on the weight tray, and the upper ball was allowed to rotate at 600 rpm. for 1 hour. The diameters of the circular scars worn on the three stationary balls were measured by means of a low power microscope. The results are shown in Table I.

The 5% by weight of the compounds of the present invention (lubricants 1, 2 and 3 in Table I) used as additives in the formulation of lubricant mixtures is arbitrary and is not intended to limit the use of the compounds to that amount. Although the amount would usually be about 5% or less, it is obvious to anyone skilled in the art that other amounts would produce desirable results.

In the wear tests, the smaller value denotes the oil with the better lubricating property. The compounds of the present invention (No. 1, 2 and 3 in Table I) and the lubricant compositions (No. 10, 11, 13, 15, 17 and 19 in Table I) formulated by the addition of the fully phosphonated ester (No. 3 in Table I) to the reference lubricants (Nos. 4, 5, 12, 14, 16 and 18 in Table I) show a very marked improvement in antiwear lubricant properties over the reference compounds. For example, when his (Z-ethylhexyl) sebacate (No. 4, Table I) was used without additive the diameter of the wear scar measured 0.830 mm. However, by adding 5% by weight of the fully phosphonated ester (No. 3, Table I) to the his (Z-ethylhexyl) sebacate, the diameter of the wear scar was reduced almost 50% to 0.442 mm. (No. 10, Table I). Another example is the paraflin oil (No. 5, Table I). Without additive, the wear scar measured 0.803 mm. in diameter. With the fully phosphonated ester (No. 3, Table I) added to it, the wear scar was only 0.460 mm. in diameter (No. 11, Table I). Other examples showing similar improvement in lubricating properties can be found in Table I.

TABLE I.-LUBRICATION AS MEASURED BY WEAR SCAR Lubricant Wear Additive Scar No. Name (5% by weight) Dia., mm.

1 Dilinoleate ester None 0. 760 2 53% phosphonated d0 0. 483

dilinoleate ester. 3 phosphonated do 0. 410

dilinoleate ester. 4 Bis (Z-ethylhexyl) .d0 0. 830

sebaeate. 5 100 paraffin oil do 0.803 6 Bis (2-ethylhexyl) Dllinoleate ester.. 0. 778

sebacate. 7 100 parafiin oil ..do 0. 597 8 Bis(2-ethylhexyl) 53% phosphonated 0. 455

sebaeate. dilinoleate ester. 9 100 paraffin oil ..do 0. 460 10 Bis(2 ethylhexyl) 100% phosphonated 0. 442

sebacate. dilinoleate ester. 11. 100 paralfin oil ..(lo 0. 460 12 Bis(benzyl) dilinoleate... None 0.653 13 ..do 100% phosphonated 0.470

dilinoleate ester. 14 Hydrogenated bis- None 0.748

(benzyl) dilinoleate. 15 ..do 100% phosphonated 0. 447

dilinoleate ester. 16..- Bis(p-isopr0pyl benzyl) None 0.843

dilinoleate. 17 do 100% phosphonated 0. 587

dillnoleate ester. 18 Dibenzyl sebacate None 0.950 19 d0 100% phosphonated 0.620

dilinoleate ester.

The extreme pressure properties were determined with a Shell Four Ball Extreme Pressure Tester also described by Peale et al. This is similar to the Wear Tester except that it is more rigidly built and made to accommodate higher loads.

This instrument was used to determine loads at incipient seizure and at welding. Incipient seizure is defined as the load at which a sudden sizeable increase in wear scar diametcr occurs, and welding is the load at which motion of the upper rotating ball in relation to the other three is no longer possible. The samples were run at room temperature under available loads for a one minute period. A fresh sample was used for each load. Rotation of the upper ball was 1700 rpm. The results, Tables II and III, show that the fully phosphonated bis(trimethylolpropane diallyl ether) dilinoleate can perform its lubricating function under much greater pressures than can the reference lubricants (No. 1, 2, 3, 4, Table II). For example, the extreme seizure load for a commercial built lubrication oil (No. 3, Table II) was 110 kg. while that of the fully phosphonated ester (No. 5, Table II) was 300 kg. Also, the pressure weld load for the same commercial oil (No. 3, Table II) was 190 kg. while that of the fully phosphonated ester of this invention (No. 5, Table II) was 350 kg.

Thermal stability was determined by the thermogravimetry, heating the compound in a specially designed sample holder suspended from a weighing mechanism. This procedure has been described by Parker, et al., I. Am. Oil Chem. Soc. 42, 792 (1965). The Onset of Decomposition for these compounds is in the range 410- 490 F. Phosphonated compounds decompose in the lower temperature range to the original dilinoleate ester. Bis- 4 D445-60 and ASTM D567-53 using Cannon-Manning semi-micro viscometers.

The compounds of the present invention have several other desirable features: (1) they are relatively high molecular weight compounds, yet they are monomers, not polymers; (2) their molecular weights can be varied in the range between 953 and 2179 depending on the extent of phosphonation, thus allowing the production of tailormade compounds with predetermined physical and chemical properties; (3) they could be expected to have the lubricating properties of an ether, an alkane or alkene and a dibasic ester and when phosphonated, those of an alkyl phosphonate; (4) they should be compatible or soluble in base oils that contain any of the above named functional groups; (5) that portion of the molecule represented by R in the unphosphonated compound has four reactive sites which may be reacted with any compound that usually adds across a double bond.

In a typical procedure for the preparation of the esters about a 2 to 1 molar ratio of alcohol to dimer acid and a small amount of an acid catalyst were dissolved in an inert organic solvent such as benzene and refluxed until the reaction was complete, as indicated by the amount of water collected. The benzene solution was washed until free of acid, dried over calcium sulfate, the benzene removed, and the crude product purified by molecular distillation.

TABLE IV.-VISCOSITY CHARACTERISTICS OF BIS(METHYLOLPROPANE DIALLYL ETHER) DILINOLEATE AND ITS PHOSPHONATED ESTER WHEN USED AS BASE OIL AND AS ADDITIVE.

Kinematic Viscosity, Sample centistokes at- Viscosity A.S.'1.M.

Index slope 37.8 0. 643 C. 98.8" C.

Dllinolcate ester (DE) 257. 8 115. 58 24. 6 118.1 0. 602 100% phosphonated dilinoleate ester PDE) 752, 4 255. 8 40. 3 105. 5 0. 638

B1s(2-ethylhexyl sebacate) (DOS). 12. 7 8.08 3. 34 154 0.710

100 pamfiin oil 51. 3 24. 7 6. 80 94. 0 0. 742

DOS +5% DE (as additive) 14. s 9.12 3. 76 175 0. 720 100 parafiin 011 +5% DE (as additive) 50. 4 24. 2 0. 78. 8 0. 778

DOS +5% PDE (as additive) 17.8 10. 9 4. 28 170 0. 672 100 paralfin 011 +5% PDE (as additrv 73. s 33. 8 8. 70 97. 9 0. 733

DOS +5% PDE-53 1 (as additive)... 14. 6 9.10 3. 158. 8 0. 688 100 paraffin 011 +5% PDE-53 (as additive) 50. 7 23. 8 6. 3G 75. 6 0. 783

l 53% phosphonated dilinoleate ester.-

(trimethylolpropane diallyl ether) dilinoleate starts to decompose at 490.

TABLE IL-COMPARATIVE FOUR BALL EXTREME PRES- SURE TEST DATA* Tests conducted at room temperature for one minute.

TABLE IIL-FOUR BALL EXTREME PRESSURE TEST DATA ON PHOSPHONATED BISQVIETHYLOLPROPANE DIALLYL ETHER) DILINOLEATE (PDE).*

N amo Percent Load, kg Scar Dia., mm.

Tests run at room temperature for one minute. 1 Incipient seizure. i Weid10 see.

The compounds have a wide range of viscosity characteristics as shown in Table IV. The viscosity of the fully phosphonated ester is similar to that of commercial lubricant additives. The kinematic viscosity, viscosity index, and the ASTM slope were determined according to ASTM In the preparation of the phosphonated esters, about one mole of the above ester was reacted with about nine moles of a dialkyl phosphonate (dialkyl hydrogen phosphate) in the presence of a peroxide catalyst. The catalyst was added in one-quarter portions at four hour intervals. The excess phosphonate was distilled off under reduced pressure, and the phosphonated ester was purified by molecular distillation. The extent of reaction was determined by infrared spectra, iodine number and percent phosphorus.

The alkyl radical of the dialkyl phosphonate can be any straight or branched chain aliphatic alkyl radical containing 1 to 8 carbon atoms such as methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl and any of their isomers. The di-Z-ethylhexyl phosphonate derivatives are used to exemplify this invention.

The dimer acid employed in the preparation of the esters contained dilinoleic acid, 4% trimer acid, and 1% monobasic acid and had the following characteristics: Acid number, 191.2; neutralization equivalent, 293.4; and molecular weight, 565: The dialkyl phosphonate (dialkyl hydrogen phosphite) was redistilled before use. Best results were obtained with use of naphthalene-Z-sulfonic acid as an esterification catalyst. Naphthalene-l-sulfonic acid, methane sulfonic acid, and sulfuric acid can also be used as the catalyst, but give poorer results than naphthalene-Z-sulfonic acid. The catalyst used for the dialkyl phosphonate addition was t-butyl perbenzoate.

Preparation of the esters is illustrated by the following examples which are not intended to be in limitation of the scope of the present invention:

EXAMPLE 1 Dimer acid, 141 g.; trimethylolpropane diallyl ether, 107 g.; and 2.8 g. naphthalene-Z-sulfonic acid were dissolved in 450 ml. benzene in a two-liter 3-neck flask. The flask was equipped with a magnetic stirrer, thermometer, and a Dean and Stark tube with a water-cooled condenser. The mixture was heated at 90 C. reflux temperature until 7.5 ml. of water was taken off in 7 hours reaction time. Since the amount of water collected indicated that the reaction had not gone to completion, an

additional 1.4 g. catalyst was added to the reaction mixture, and the rejuvenated reaction gave off an additional 1.5 ml. water in 2 hours. Total reaction time: 9 hours; total weight of catalyst, 4.2 g. After cooling, the reaction mixture was washed with water until acid-free. The benzene solution was dried over calcium sulfate, filtered, and the benzene evaporated under vacuum. The crude product, a dark amber fluid, weighed 233.5 g., percent yield, 96.6; acid number, 5.5; n 1.4776.

The crude product was purified by molecular distillation, the main fraction being collected above 225 C. at 7 micron pressure. This fraction weighed 101 g. The purified product, bis(trimethylolpropane diallyl ether) dilinoleate, a medium amber liquid had the following characteristics: n 1.4782; iodine number 135.1; saponification number 121.1 calcd., 117.7; saponification equivalent 465.5. calcd., 476.8; percent carbon 75.78, calcd., 75.88; percent hydrogen, 11.08, calcd., 10.99; molecular weight, 931, calcd., 953.

EXAMPLE 2 Bis(trimethylolpropane diallyl ether) dilinoleate, 50 g.; di-Z-ethylhexyl phosphonate, 144 g., and one-quarter of the total amount (4.6 g.) of t-butyl perbenzoate were mixed in a 500 ml. 3-neck flask. The flask was equipped with a magnetic stirrer, water condenser, thermometer, and gas inlet tube. The reaction mixture was blanketed with nitrogen until the reaction was completed. While the reaction mixture was heated at 110 C. for 16 hours, onequarter portions of the catalysts were added at four hour intervals. After each catalyst addition, except the last, the reaction temperature rose 5-6 degrees. The last addition resulted in only a two-degree rise. The reaction mixture was degassed in a molecular still at room temperature under a partial perssure. The excess phosphonate was distilled off at 120150 C. at microns pressure. The main fraction, a viscous amber liquid, was collected above 200 C. at 7 microns. The purified product weighed 65.0 g.; percent carbon, 71.42, calcd., 68.34; percent hydrogen, 11.15, calcd., 11.29; percent phosphorus, 3.03, calcd., 5.68; iodine number, 75.7. The infrared spectra, iodine number, and the percent phosphorus indicated that the compound had attained 53% of the maximum amount of dialkyl phosphonate addition.

EXAMPLE 3 The procedure of Example 2 was repeated except that the reaction time was increased to 32 hours and 1.1 g. catalyst was added at 4 hour intervals (Total amount, 9 g.). Molecular distillation, above 240 C. at 7 microns pressure, yielded a very pale amber viscous liquid. The purified product weighed 60.0 g.; percent yield, 52.6; iodine number 20.7; n ,1.4755; percent carbon, 67.82, calcd., 68.34; percent hydrogen, 10.99, calcd., 11.29; percent phosphorus, 5.64, calcd., 5.68; molecular weight, calcd., 2179. The iodine number and percent phosphorus indicated that the ester had been phosphonated 100%.

Since both the 53% and the 100% phosphonated derivatives are markedly improved lubricants over the unphosphonated compound and over the reference lubricants (Table I), it is considered that any products in the range of about from 50% to 100% phosphonated compounds are operative in the present invention.

We claim:

1. A mixture of compounds of the formula C2115 CH2OCH2-R C R- OCHz CH2OCH2-R' 2 wherein R is the diacyl radical of dimerized linoleic acid and each R is a member selected from the group consisting of -CH=CH and wherein R" is a member selected from the group consisting of straight and branched chain aliphatic alkyl radicals containing from 1 to 8 carbon atoms.

2. The mixture of compounds of claim 1 wherein R" is 2-ethylhexyl.

3. The mixture of compounds of claim 2 wherein R' is 47% CH =CH and 53% 4. A lubricant composition comprising about 5% by weight of the mixture of compounds of claim 3 and about by weight of a base oil selected from the group consisting of bis(2-ethylhexyl) sebacate and parafiin oil.

5. The lubricant composition of claim 4 wherein the base oil is bis(2-ethylhexyl) sebacate.

6. The lubricant composition of claim 4 wherein the base oil is 100 paraflin oil.

7. A lubricant composition comprising about 5% by weight of a compound of the formula wherein R is the diacyl radical of dimerized linoleic acid and R is -CH=CH and about 95 by weight of a base oil selected from the group consisting of bis(Z-ethylhexyl) sebacate and 100 parafiin oil.

8. The lubricant composition of claim 7 wherein the base oil is bis(2-ethylhexyl) sebacate.

9. The lubricant composition of claim 7 wherein the base oil is 100 paraffin oil.

10. A lubricant composition comprising about 5% by weight of a compound of the formula wherein R is the diacyl radical of dimerized linoleic acid and R is wherein R" is a member selected from the group consisting of straight and branched chain aliphatic alkyl radicals containing from 1 to 8 carbon atoms, and about 95 by weight of a base oil selected from the group consistipg of bis(2-ethylhexyl) sebacate, 100 paraffin oil, bis(benzyl) dilinoleate, hydrogenated bis(benzyl) dilinoleate, bis(pisopropyl benzyl) dilinoleate, and dibenzyl sebacate.

11. The lubricant composition of claim 10 wherein R" is 2-ethylhexyl.

12. The lubricant composition of claim 11 wherein the base oil is bis(2-ethylhexyl) sebacate.

13. The lubricant composition of claim 11 wherein the base oil is 100 paraffn oil.

14. The lubricant composition of claim 11 wherein the base oil is bis(benzyl) dilinoleate.

15. The lubricant composition of claim 11 wherein the base oil is hydrogenated bis(benzyl) dilinoleate.

16. The lubricant composition of claim 11 wherein the base oil is bis(p-isopropyl benzyl) dilinoleate.

17. The lubricant composition of claim 11 wherein the base oil is dibenzyl sebacate.

References Cited UNITED STATES PATENTS 2,411,178 11/1946 Young et a1. 25257 2,673,184 3/1954 Morway et a1 2S2--57 XR 3,039,967 6/1962 Henry et a1 25257 XR 10 DANIEL E. WYMAN, Rrimary Examiner.

W. H. CANNON, Assistant Examiner.

U.S. Cl. X.R. 

